Speaking serial out RJ-45 jack

[Richard Esplin]

I need to talk to a Cisco 2600. It has an RJ-45 jack on it, and it comes with 
an RJ-45 to D9 cable. My laptop does not have a D9 serial port.

I know that I can buy a USB to serial dongle.

However, in theory I can just tell my computer to speak serial out my ethernet 
port.

Is there a driver that does this? I'm running Ubuntu Hardy, but I'm curious if 
it exists anywhere.

I understand that I can get software that lets me transmit serial over 
ethernet to another machine which will then send it out the serial port. That 
isn't exactly what I want.

Any ideas?

Thanks,

Richard Esplin